2.Intensity

We will use a Low intensity. More exactly, up to 25% of maximum grip force (To learn why we choose a % of maximum strength over maximal oxygen consumption or maximum heart rate like they do in other sports, have a look at this entry).

2.1 Why topping at 25% of maximum grip strength?

We will lean on a number of related conclusions:

a) Some authors suggest that 25% of MVC is the highest intesity where the aerobic metabolism is still the main energy source (Fallentin et col., 1993; Byström, 1994; Kimura et col., 2006), and that is the one we want to optimize here (Usaj et col., 2007; Fryer et col., 2014).

b) One of the stimuli that lead to changes in the blood vessels surrounding certain muscle fibers (angiogenesis and arteriogenesis, see previous entry) is the repeated and sustained increase of blood flow in the area (Hudclicka et col., 1992; Prior et col., 1997, Egginton et col., 2001, Hounker et col., 2003) characteristic of aerobic exercise at the aforementioned intensities.

One could think that a higher demand on the muscles would increase even more their need for energy and hence blood flow. By the contrary, in isometric contractions maximal blood flow is registered at very low intensities: around 10-25% of MVC. Past this, at 25-40%, the flow does not actually go up, and it even decreases if we go further (Barnes, 1980; Byström and Kilbom, 1990). Let's explain why:

On the one hand there has been found a direct association between the intensity of a contraction and blood flow (Sjøgaard, Fagard & Fuel, 1988; Byström & Kilbom, 1990); also between the duration of a contraction and blood flow during the interval between contractions, as well as during recovery after exertion (Byström & Kilbom, 1990; Laughlin et col., 1999).

On the other hand, though, the harder the contraction, the more intramuscular pressure (Barnes et col., 1980; Sejersted et col., 1984; Thompson et col., 2007). When it comes to isometric contractions a problem arises: the blood vessels get occluded for several seconds, compromising nutrient exchange. This leads to a buildup of liquid as well. According to some authors, this explains isometric fatigue (Sjøgaard, Fagard & Fuel, 1988; Kalliokoski et col., 2003).

More specifically, tests performed with a dynamometer on the muscles of the forearm have found that the blood occlusion starts at 30% of MVC, and is complete at 50-70% (Barcroft & Miller, 1939; Barnes, 1980; Sjøgaard et col., 1998).

2.2 The usual problem... How do we control the intensity during a training session?

From a practical point of view, what kind of holds and what climbing styles do I have to favor?

Looking at what we have already seen we should go for holds that, being on a particular wall, wouldn't represent more than 25% of our maximum grip strength.

a) One possible solution would be to perform a test of maximum climbing time on a certain kind of hold, and looking at the relationship found by Rohmert (1960) and confirmed by successive authors (Allison et col., 2004; Frey & Avin 2010; Looft, 2012) between percentage of MVC during an isometric contraction and maximum duration of such contraction. In short, the higher the intensity the quicker the exhaustion and vice versa. This can also be applied to the number of repetitions/sets in dynamic exercises:

All these figures have to be taken with a grain of salt, though, because:

i) The participants were untrained people for whom the forearm muscles were not a key performance factor.

ii) There is great variability in low intensity endurance among individuals.

iii) The dyamometer is not considered a specific tool to measure maximum grip strength in climbing (Watss, 2004) neither to assess actual climbing performance. In this regard, we don't know about any climbing-oriented tests that measure maximum time for a wide variety of intensities during real climbing.

Recently López-Rivera, E. (2014) has put forward in her PhD thesis a formula for estimating maximum hang-off duration as a function of edge depth (6-14 mm) and sport level (6b+ to 8c+, n=36), but it is probably valid for higher intensities only (we will go over it in the entries about high intensity endurance) and it remains to be seen its application to actual climbing on holds of similar size to the test ones.

The goal is to find holds and walls of a certain angle that allow us to endure the programmed climbing time at a low intensity:

For low-mid level or high volume sessions, we will probably choose the largest holds, those deep enough to fit the entire fingers, with a positive and rounded profile (jugs), on vertical or less than vertical walls. For higher levels the holds could be similar, but the wall more steep or overhanging. Trying holds not so deep is a possibility. Anyway, each climber will have to test it...because as you already know, individualization and control of the training load is key for an effective training.

We will learn to associate low intensity to a set of sensations that can be described as follows.

2.2.2 Sensations related to the Physiological Effects of Capacity Training

Several authors have assessed the validity of subjective scales of perception to control the intensity in different sports (Seyler, S. in Mujika, 2012 [editor]). To develop our Capacity we have to look for and maintain the following sensations:

Local signs at the forearms:

Moderate swelling and activation, never stiffness and strong pumping. As we progress in time or sets we may need to shake off every 2-3 moves for 1-2 seconds.

Some vasodilation that can translate into "heat", reddening, bulging veins...

Progressive "depletion" (according to the objectives for the session).

As the session progresses, especially at the end of every set, it is normal to notice our movements are "slower", perhaps due to some related factors: a) we start running out of glycogen and use slow-burning fatty acids, b) we need to save energy and the kind of holds we are using allows us to do that, and c) because this way we can relax the free hand a bit longer. When climbing easy parts our hand can stay free for about 0,5 seconds, but it can go up to 1-2 seconds if we climb slower, giving time to the forearm to recover and keep on functioning.

Note: In the future we will publish an entry discussing a proposal for a load control scale in climbing training.

3. Volume

From 10 to 40-60 minutes, attending to the use of continuous or interval methods, our level, our training experience, climbing projects and time of the season, etc.

The next post will expand on the continuous and interval methods, and will offer some guidelines to customize total volume, number of sets, rest pauses, etc.

Byström, SEG, and Kilbom, Å (1990). Physiological response in the forearm during and after isometric intermittent handgrip. European journal of applied physiology and occupational physiology, 60(6), 457-466.

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